Hi,

When I run the below test, occasionally the CPU time of process B is high.

Process A:
for ( unsigned long i=0; ; i++)
{
mq_send( mq_a, ...)
if ( ! (i/15) ) sleep for 1/1000 seconds
}

Process B:
while(1)
{
mq_receive( mq_a, ...)
}

In most of the testings, the CPU time consumted by either process A or B is quite low. But occasionaly (2 or 3 times in 10 testins), process B consumes a high CPU time, say 30% ~ 50%), mainly because of high sys time.

Could anyone share with me why the CPU time for process B is high? busy waiting the lock in kernel mode? And how to solve this issue?

The testing environment: CPU - 2 cores, linuex - redhat, message queue is NOT set to NONBLOKCED.

Thanks,
Jack